Hmm. Leaving aside just for a moment any problems with finding data that
supports the contagation properties of this pathogen in a virgin soil
population which pre-date Columbian contacts, as well as the possible
errors in determining one agent for skeletal lesions from others, areas
others in s.a.m, and I presume s.a.p specialize in, there is another
problem with "opportunity" -- contagation expansion and rebound and the
time required to return to steady-state _and_ the apparent non-establishment
of this (and several others) pathogens as endemic in the pre-Columbian
population groups, whether assumed to be relative isolates or assumed to
have trade/contact with regionally proximal peoples, hence non-isolates,
other than w.r.t. Old World (domestication consequent) pathogens. Nice
long sentance there.

So _if_ the opportunity ever was realized, using _any_ of the assumptions
available as to the size and regional isolation and even pre-modern properties
of jrandom contact-pathogen, if any even may have existed different from the
properties presently manifested (incubation period, contagation vectors,
mobidity and mortality, everything except divine intervention), just how
many centuries prior to the Columbian contact and its apparent conditions
(absence of pathogen X "immunity", actually non-leathal pre-exposure) is it
necessary to set the latest date at which the hypothetical contagation-
realized pre-Columbian contact(s) could have occured?

Keep in mind that an accurate pop model needs to match reality at two points:
the known inputs (properties of the pathogen under hypothetical study), and
the known end-condition (steady-state transition to collapse in the 16th
century, whether in the Valley of Mexico or New England, or 18th century and
later oceanic isolates). Between those two one is free to create populations
of arbitrary sizes and arbitrary isolation. Conditions that support a "near"
dating of pre-Columbian pathogen transimission and meet both "fixed points"
do not appear to be supported by the archaeological record, e.g., high
degree of regional isolation, very low host populations, no trade of regional
consequence, and some fairly difficult reproductive replacement strategies.

I ought to do a paper on this, but I'm lazy enough to ask if anyone else
has, basically, anyone have a pointer to pathogenic population modeling
either in the arch or public health literatures?